The invention relates to a machine for making a fiber web with sharply defined edges, specifically a paper or tissue web, between a felt and a wire; said machine features a headbox that dispenses the fiber suspension into a feed-in area formed between the felt and the wire.
Typically, the paper web formed by paper machines is normally made oversize in the width or lateral dimension. The irregular thin edges of the finished web are then trimmed off and recycled to the stock preparation system of the machine. However, sharply defined edges can also be made by separating the edges from the wet web by means of a thin jet of water.
An example of the above type machine is disclosed in German Patent Publication No. 15 61 669 wherein an attempt is made at obtaining sharp web edges by providing in the web forming wire a small sealed band near each edge of the wire whereby the wire is impermeable over a slight width at each edge. Thus, no web formation occurs on these sealed bands and the edge strips produced outside of the sealed bands are not connected with the web. A drawback with this type of machine is that the edge strips, which are already separated in the web formation zone, will be picked up by the receiving felt and carried through the machine and can been discarded only after the first drying cylinder. Consequently, part of the machine width and energy is unnecessarily used for handling the already-separated edge strips.